The invention relates to a guide vane for a diffuser of a radial compressor.
Such guide vanes for diffusers of radial compressors are already well known from the general prior art. The radial compressor usually has a receiving region, in which a compressor wheel of the radial compressor can be received or—in the finished state of the radial compressor—is received. Furthermore, the radial compressor has a diffuser arranged downstream of the receiving region which extends, for example, at least substantially in a radial direction. During the operation of the radial compressor, air which flows off from the compressor wheel and flows through the diffuser is compressed by means of the compressor wheel.
The aforementioned guide vane can be arranged in the diffuser, which is constructed for example as a radial diffuser, or is arranged therein—in the finished state of the radial compressor—and serves for guiding the air flowing through the diffuser. In this case the guide vane has a skeleton line, wherein the guide vane can be constructed, for example, as an aerofoil.
Usually a plurality of guide vanes are arranged in the diffuser, being arranged in the circumferential direction of the compressor wheel successively over the circumference thereof. The plurality of guide vanes form a guiding means which is also designated as a discharge guide vane. The guiding means is arranged in the flow direction of the air downstream of the compressor wheel or of the receiving region and ensures advantageous flow conditions in the diffuser.
Furthermore, WO 2006/053579 A1 discloses a turbocharger having a turbine which comprises a turbine wheel and a guide vane assembly arranged upstream of the turbine wheel and having a plurality of guide vanes.
Conventional guide vanes, which are used in conventional radial compressors and are arranged or can be arranged in the diffuser, have vane geometries which lead to unfavorable and thus disadvantageous flow conditions in the diffuser. Such a vane geometry is, for example, a geometry in the form of a droplet profile, which leads to a substantial narrowing of the flow channel through which the air can flow, so that only a small maximum mass flow of the air can flow through the flow channel. A further vane geometry is the so-called NACA profile, which is optimized for aircraft wings, but creates high losses in the diffuser. A further vane geometry is the so-called wedge vane, which leads to substantial losses due to a sudden enlargement of the channel at the vane end. If the respective guide vane is configured, for example, as a straight vane with a constant thickness, this leads to an undesirably significant deceleration of the flow of air, resulting in high losses. A further vane geometry is the so-called circular arc geometry with a constant thickness. In this case there are only an insufficiently large number of free geometry parameters and this vane geometry leads to significant decelerations, in particular in the central part of the guide vane.
Therefore, the object of the present invention is to further develop a guide vane of the type mentioned above in such a way that particularly advantageous flow conditions can be obtained in the diffuser.
In order to further develop a guide vane in such a way that particularly advantageous flow conditions can be obtained in the diffuser, it is provided according to the invention that the skeleton line is configured elliptically at least in a part-region.
It has proved particularly advantageous if the entire skeleton line, that is to say along its entire extent, is configured elliptically. Due to the use of a guide vane with an elliptical skeleton line, an at least almost uniform deceleration in a flow channel delimited at least partially by the guide vane can be obtained without an excessive constriction occurring at the front edge of the vane. Furthermore, due to the use of a guide vane with an elliptical skeleton line there are a large number of free geometry parameters.
The invention also comprises a radial compressor, in particular for an exhaust gas turbocharger of an internal combustion engine, with a receiving region for a compressor wheel of the radial compressor, with a diffuser arranged downstream of the receiving region, and with at least one guide vane according to the invention arranged in the diffuser.
The diffuser per se is a flow channel through which air can flow, wherein the air is compressed by means of the compressor wheel, flows off from the compressor wheel and flows through the diffuser. Because the guide vane has at least one substantially elliptical skeleton line, particularly advantageous flow conditions can be obtained in the diffuser without excessive disadvantages, so that a particularly efficient operation of the radial compressor can be produced.
Further advantages, features and details of the invention can be seen from the following description of a preferred exemplary embodiment and with reference to the drawing. The features and combinations of features set out above in the description and the features and combinations of features set out below in the description of the drawing and/or shown in the single drawing can be used not only in the specified combination in each case, but also in other combinations or in isolation without departing from the scope of the invention.